1. Field of the Invention
The present invention relates to an optical waveguide such as an optical fiber, a thin-film waveguide, etc., and more particularly to a waveguide member for producing a diffraction grating in a predetermined portion while changing the index of refraction periodically, an optical waveguide in which the diffraction grating is built, and a process for producing it.
2. Related Background Art
There are a variety of forms in which a diffraction grating is built as a kind of optical component. When utilized for example in an optical communication system, particularly, a suitable one is of an optical waveguide type which is easy connect with another optical waveguide and in which the diffraction grating is built in order to lower an insertion loss.
A conventionally known process for producing the optical waveguide having the diffraction grating is for example one described in Japanese Laid-open Patent Application No. 62-500052. This is a method for producing the diffraction grating in such a manner that a quartz-base optical fiber is formed with a high-refractive-index core doped with germanium dioxide and that the optical fiber is then irradiated with strong ultraviolet light so as to produce a periodic index change in the core to form the diffraction grating.